Section 2: Design Exceptions, Design Waivers and Design Variances

Overview

Design Exceptions

A design exception is required whenever the criteria for certain
controlling criteria specified for the different categories of construction
projects (i.e., 4R, 3R, 2R, Special Facilities, Off-System Historically
Significant Bridge Projects, Park Road Projects, and on-street Bicycle
Facilities) are not met. The determination of whether a design exception
exists rests with the district, unless the project is subject to
federal oversight or review. A design exception is not required
when values exceed the guidelines for the controlling criteria.

Design exceptions for plans, specifications and estimates,
designated federal oversight under the current Federal Oversight
Agreement must be reviewed and approved by the FHWA. Design exceptions
for all schematics on the NHS with the exception of preventive maintenance,
freeway safety and 3R type projects must be reviewed and approved
by the FHWA.

Design exceptions for all projects on the interstate system
must also be reviewed and approved by the FHWA.

Design exceptions involving the structural capacity or bridge
width shall be sent to the Bridge Division for their review and
approval.

Final approval of a roadway design exception must be signed
by the district engineer and this signature authority cannot be
delegated. For flexibility and efficiency in meeting project design schedules,
the review of design exceptions and recommendations for approval/non-approval
may be established individually by each district. For example, a
four person review committee might be established which includes:

Director of Transportation Planning
and Development,

Director of Construction,

Director of Operations/Traffic, and

Area Engineer (not responsible for project management).

The reviews of any three of the four member committee would
constitute a quorum for recommending signature action.

The complete documentation for a roadway exception should
be retained permanently in the district project files and a copy
furnished to the Design Division. Since the construction plans are sealed,
the design exception documentation does not require an engineer’s
seal.

The following project categories will have controlling criteria
that dictate a design exception.

New Location and Reconstruction Projects (4R).
The list below gives the controlling criteria that will require
a design exception.

Resurfacing, Restoration or Rehabilitation (3R)
Projects. The list below gives the controlling criteria
that will require a design exception. For 3R projects, high volume
roadways are defined as current ADT of 1500 and greater.

Resurfacing or Restoration Projects (2R).
Design exceptions are required for 2R projects any time the existing
geometric or bridge features for the proposed project will be reduced.

Special Facilities. For off-system bridge
replacement and rehabilitation projects with current ADT of 400
or less, the following design elements must meet or improve conditions
that are typical on the remainder of the roadway or a design exception
will be necessary:

Park Road Projects. Design exceptions
are not applicable to park road projects that are off the state
highway system. Design is based on the criteria and guidance given
in the current publication of the Texas Parks and Wildlife
Department Design Standards for Roads and Parking,
or as approved by the Texas Parks and Wildlife Department.

On-system park road projects must meet the required design
criteria for the appropriate roadway classification including exception
or waiver requirements.

Bicycle Facilities. Design exceptions
are necessary when the minimum requirements given in the AASHTO Guide
for the Development of Bicycle Facilities for on-street bicycle
lanes and increased shared lane width cannot be met.

Design Waivers

When the criteria is not met in a noncontrolling category,
a design exception is not required. However, variations from the
criteria in these cases will be handled by design waivers at the
district level. Design waivers will be granted as the district authorizes.
The complete documentation should be retained permanently in the
district project files and a copy furnished to the Design Division.

The following project categories will have noncontrolling
criteria that dictate a design waiver.

New Location and Reconstruction Projects (4R). The
list below gives the noncontrolling criteria that will require a
design waiver:

Resurfacing,
Restoration or Rehabilitation (3R) Projects. The list
below gives the noncontrolling criteria that will require a design
waiver. For 3R projects, low volume roadways are defined as current
ADT of less than 1500.

Design Variances

A design variance is required whenever the design guidelines
specified in the Americans with Disabilities Act Accessibility
Guidelines (ADAAG) and the Texas Accessibility Standards
are not met. Design variances should be sent to the Design Division
for forwarding to the Texas Department of Licensing and Regulation
for approval. Refer to
Sidewalks
and Pedestrian Elements in Chapter 2 for additional discussion.